Children in foster care are more vulnerable to poor health than any other group of children in the United States. They have experienced many threats to their health such as abuse and neglect, and have significantly higher rates of all physical, mental health, and developmental problems. Adolescents additionally experience multiple placement transitions, involvement in multiple systems of care (e.g., mental health, juvenile justice, special education), and aging-out of foster care at age 18 before they are developmentally ready for independent living. There are few health care professionals to manage the complex health and developmental needs of these adolescents; therefore, creative collaborative models are needed to maximize the impact of nursing expertise to serve these vulnerable youth. The purpose of this proposed five-year longitudinal experimental study is to test the effectiveness of a nursing intervention for court appointed special advocates (CASA) on the physical health, mental health, and social development outcomes of adolescents in foster care. The CASA is a community volunteer who advocates for the needs of one individual adolescent in foster care. The intervention group will be adolescents (ages 12-18) in foster care assigned to a CASA who will have bimonthly intensive consultation, health education, and support by nurses and complex case consultation by physicians for two years. The control group will be adolescents in foster care assigned to a CASA who receives only the standard CASA training and a brief control group intervention. Baseline and outcome measures at one and two years of the intervention will be given to both groups of adolescents, including the Child Health and Illness Profile (physical health), Child Behavior Checklist (mental health), and Interpersonal Competence Scale (social development). Repeated measures analysis of variance will be used to test study hypotheses. This study is innovative because foster youth health has not been a primary focus of nursing research or CASA advocacy efforts, and CASA impact on adolescent health outcomes has not been investigated.